U.S. patent number 3,942,337 [Application Number 05/506,601] was granted by the patent office on 1976-03-09 for torque limiting device.
This patent grant is currently assigned to Industrial Analytics Inc.. Invention is credited to Ralph R. Leonard, Ted J. Taylor.
United States Patent |
3,942,337 |
Leonard , et al. |
March 9, 1976 |
Torque limiting device
Abstract
A torque limiting device employing a clutch disposed within a
cylindrically shaped housing and coupling first and second members
coaxially mounted in the respective ends of the cylindrically
shaped housing. The first and second members are rotatably mounted
in the housing and adapted for engagement with the torqueing device
and work respectively or vice versa. Manual rotation of one housing
section relative to the other housing section adjusts to
predetermined maximum value the torque which is transmitted through
the device, viz., between the first and second members.
Inventors: |
Leonard; Ralph R. (Kent,
WA), Taylor; Ted J. (Seattle, WA) |
Assignee: |
Industrial Analytics Inc.
(Kent, WA)
|
Family
ID: |
24015264 |
Appl.
No.: |
05/506,601 |
Filed: |
September 16, 1974 |
Current U.S.
Class: |
464/36 |
Current CPC
Class: |
B25B
23/141 (20130101); F16D 7/044 (20130101); F16D
7/08 (20130101); Y10T 74/18304 (20150115) |
Current International
Class: |
B25B
23/14 (20060101); F16D 7/04 (20060101); F16D
7/00 (20060101); F16D 7/08 (20060101); F16D
007/06 () |
Field of
Search: |
;64/29 ;192/56R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Herrman; Allan D.
Attorney, Agent or Firm: Gardner; Conrad O.
Claims
What is claimed is:
1. A torque limiting device comprising in combination:
a cylindrically shaped housing comprising first and second cup
shaped sections, said first cup shaped section having an outer
threaded surface around the lip portion thereof, and said second
cup shaped section having a mating internal thread around the lip
porition thereof, said first section rotatable relative to said
second section about the axis of said cylindrical housing;
first and second shafts disposed along the axis of said cylindrical
housing, said first shaft rotatably supported in the bottom of said
first cup shaped section, and said second shaft rotatably supported
in the bottom of said cup shaped second section;
a clutch assembly disposed in said housing and interconnecting said
first and second shafts, said clutch assembly including two clutch
members operative to separate and break the interconnection between
said first and second shafts when the torque resistance to rotation
of said first or second shaft exceeds a predetermined level;
and,
said rotation of one of said cup shaped sections relative to the
other providing adjustment of the gap between said two clutch
members.
2. A torque limiting device having means for selecting any torque
limit value between minimum and maximum torque limit capabilities
of said device comprising:
an input shaft adapted for transmission of torque by means of a
supplemental torqueing tool;
an output shaft adapted for coupling to a workpiece;
a housing surrounding said input and output shaft, said housing
comprising first and second sections, one of said sections
rotatable relative to the other section;
a clutch assembly disposed in said housing and interconnecting
input and output shafts, said clutch assembly including two clutch
members operative to separate and break the interconnection between
said input and output shafts when the torque resistance to rotation
of said input or output shaft exceeds a preselected torque limit
value;
compressive spring means within said housing responsive to hand
rotation of one of said housing sections relative to the other for
providing a compressive force through a first of said two clutch
members against the second of said two clutch members throughout
the adjustable torque limiting range of said device; and,
further including a compressive spring assembly within said housing
for resisting separation of the variable gap existing between said
two clutch members when the applied torque is transmitted by said
input shaft to said output shaft.
3. A torque limting device comprising:
first and second clutch members having facing surfaces;
a two section cylindrical housing have one part rotatable relative
to the other for increasing or decreasing the variable gap which
exists between the facing surfaces of said first and second clutch
members when applied torque is transmitted through the device;
compressive spring means disposed within said housing responsive to
hand rotation of one of said two housing sections relative to the
other for providing a compressive force through a first of said two
clutch members against the second of said two clutch members
throughout the adjustable torque limiting range of said device;
and, further including
a compressive spring assembly disposed within said housing for
resisting separation of the variable gap between said two clutch
members when the applied torque is transmitted through said
device.
4. A torque limiting device having means for selecting any torque
limit value between minimum and maximum torque limit capabilities
of said device comprising:
an input shaft adapted for transmission of torque by means of a
supplemental torqueing tool;
an output shaft adapted for coupling to a workpiece;
a two section housing surrounding said input and output shafts, one
of said two sections rotatable relative to the other for
controlling the variable gap between the facing surfaces of first
and second clutch members when applied torque is transmitted
through said device;
said first and second clutch members fixed to said input and output
shafts respectively, and said clutch members disposed within said
two section housing;
a wave spring coaxially disposed about the central axis passing
through said input and output shafts of said device, said wave
spring responsive to hand rotation of said one of said housing
sections relative to the other for providing a compressive force
through a first of said two clutch members against the second of
said two clutch members throughout the adjustable torque limiting
range of said device; and,
a plurality of conical shaped spring washers coaxially disposed
about said central axis for providing compressive spring force for
resisting separation of the variable gap between said two clutch
members when the applied torque is transmitted through the
device.
5. A torque limiting device having a two section housing, one of
said two sections hand rotatable relative to the other section for
adjusting the torque limit to a selected value, said device further
including:
a clutch assembly comprising a pair of clutch members disposed
within said housing, said clutch members operative to separate the
variable gap therebetween and break the interconnection between
input and output shafts connected to said clutch members
respectively when said selected torque limit is exceeded;
a first spring means comprising a spring disposed within said
housing and responsive to hand rotation of one of said housing
sections relative to the other for providing a compressive force
through a first of said two clutch members against the second of
said two clutch members throughout the adjustable torque limiting
range of said device; and further,
second spring means comprising a plurality of conical shaped spring
washers coaxially disposed within said housing for resisting
separation of the variable gap existing between said two clutch
members when applied torque is transmitted through said device.
Description
This invention relates to a torque limiting device and, more
particularly, to such a device which is manually adjustable to the
maximum torque desired and may be positioned by a mechanic between
his ratchet handle and socket to prevent the application of
excessive force to a nut, bolt, or other work.
The prior art including, e.g., U.S. Pat. No. 2,151,953 to
Zimmerman, U.S. Pat. No. 2,250,736 to Torresen, and U.S. Pat. No.
3,691,826 to Graborac, show torque indicating, measuring, and
limiting devices and may be contrasted to the present device which
may be adjusted manually to a selected maximum torque by simple
rotation of one section of the housing relative to the other
section to a corresponding vernier setting between the housing
sections.
Accordingly, it is an object of this invention to provide a
compact, self-contained torque limiting device having a variable
torque limit easily set by hand manipulation of the housing and
which can be readjusted without uncoupling the device from the
torqueing force driving it and the object being torqued.
It is another object of this invention to provide a torque limiting
device which may be inserted between a torque transmitting source
and a torque receiving device and which will limit torque in either
a clockwise or counterclockwise direction.
It is a further object of this invention to provide a torque
limiting device which incorporates repetitive reset when the torque
limit set has been exceeded.
It is still another object of this invention to provide an
adjustable torque limiting device wherein the torqueing force may
be coupled at either end of the cylindrical housing with the work
coupled to the opposite end.
It is yet another object of the present invention to provide an
adjustable torque limiting device wherein the housing may be held
fixed as by the hand of an operator while guiding the application
of the torqueing force through the driven rotating member at one
end of the housing to a receiving rotating member at the other end
of the housing connected to the work.
According to the present invention the torque limiting device
includes a clutch, the clutch members are coaxially disposed within
a cylindrically shaped housing and one of said clutch members is
fixed against axial movement within the housing while axial
movement of the other clutch member away from said one of said
clutch members is resisted by a compressive spring force which is
adjustable to provide a corresponding torque limit by rotating one
section of the cylindrically shaped housing a predetermined
distance relative to the other section. A plurality of bearings are
disposed in recesses formed between the opposing surfaces of the
clutch members and when the applied torque slightly exceeds the
selected compressive spring force, torque transmission momentarily
ceases, while the bearings in the recesses in the surface of a
clutch member move out and circumferentially a predetermined
distance between recesses and into the next sequence of recesses on
the clutch member, thereby providing automatic reset without
exceeding the selected torque setting.
In a preferred embodiment the compressive spring force is provided
by a stack of compression springs coaxially disposed about the
central axis of the cylindrical housing and intermediate the clutch
member disposed for axial movement and an inner end wall of said
cylindrical housing.
The present invention will be further described by way of example
with reference to the accompanying drawings in which:
FIG. 1 is a front elevational view of a torque limiting device in
accordance with an embodiment of the present invention;
FIG. 2 is a front elevational view partially in section of the
embodiment shown in FIG. 1;
FIG. 3 is an exploded isometric view of the internal clutching
mechanism portion of the device shown in FIG. 2;
FIG. 4 shows an exploded isometric view of the spring assembly for
generating compressive spring forces in the device shown in FIG.
2;
FIG. 5 is a view taken in section of a portion of the clutch
mechanism shown in FIG. 2 showing the disposition of the parts for
the condition of minimum torque limit setting; and
FIG. 6 is a view taken in a section of a portion of the clutch
mechanism shown in FIG. 2, however, showing the disposition of the
parts for the condition of a maximum torque limit setting.
Turning now to FIG. 1, the cylindrically shaped housing for the
device is seen to comprise a first cup shaped section 1 having an
outer threaded surface 31 (see FIG. 2) on the cylindrical portion
thereof which is rotatably supported within the overlying mating
inner threaded surface 33 of second cup shaped section 2. A first
member 35 disposed coaxially about the central axis 37 of the
device is shaped at one end into a conventional socket engaging
stud 3 projecting from the end of cylindrically shaped housing
section 1 while the other end of first member 35 within cylindrical
housing section 1 includes a first disk shaped clutch member 38
which clutch member is fixed against axial movement since at least
a certain minimal force is exerted at all times as hereinafter
described by the opposing face surface of second clutch member 40
against bearings 7 pressing on the face surface of first clutch
member 38. Actually, briefly in passing, wave spring 9 sandwiched
between washers 10 as seen in FIG. 2 (and in more detail in FIG. 4)
exerts a small compressive force through second clutch member 40
and bearings 7 against the face of clutch member 38 so that all
bearing 7 surfaces remain in physical contact with the opposing
surfaces of both clutch members 38 and 40 throughout the adjustable
torque limiting range of the device. A bushing 15 of a material
exhibiting low frictional properties which is seated in the end of
cylindrical housing section 1, surrounds first member 35 permitting
easy rotation thereof and prevents axial movement of clutch member
38 due to the aforementioned small compressive force against the
face thereof which is resisted by the portion of bushing 15
extending between the outer face 41 of clutch member 38 and the
inner end wall 43 of cylindrical housing section 1. Second member
55 has a second disk shaped clutch member 40 terminating one end
thereof within the cylindrical housing, and the other end 4 exposed
through the bottom of cylindrical housing section 2 is rotatingly
supported similarly as member 35 by a bushing 25 which is adapted
to receive the socket engaging stud of a conventional socket
wrench.
It can be noted from an observance of parts making up the torque
limiting device within the cylindrically shaped housing as shown in
FIG. 2 that the clutch assembly includes a pair of clutch members
40 and 38 having opposing driving faces containing recesses 47 and
49 respectively (see also FIG. 3) which are separate particularly
formed recesses (V-shaped slots in the configuration shown)
extending radially and equiangularly displaced around the
circumference of the facing surfaces of the respective disk shaped
clutch members, one face surface being the mirror image of the
other in this particular embodiment. There are twelve V-shaped
slots in each clutch member face surface and twelve ball type
bearings 7 distributed one in each slot. A spacer, member 6, (seen
in more detail in FIG. 3) disposed between the opposing face
surfaces of clutch members 38 and 40 and having a plurality of
slots equal to the number of bearings (here twelve) around the
periphery thereof is required to maintain the proper positioning of
ball bearings 7. Its purpose is to fix the radial distance of the
bearings 7 from the center of the disk shaped clutch members 38 and
40 so that the bearings may be stepped over a surface area 59
between slots negotiated upon reaching the torque limit set and to
thereby enable proper recycling of the device. While a particular
form of recesses 47 and 49 (V-shaped slots) are shown and bearings
cooperating therewith, another shape bearing could require another
slot configuration and might be utilized. An exploded view of the
internal clutching mechanism of the device of FIG. 2 showing parts
in isometric deemed helpful in further identifying the internal
working parts is shown in FIG. 3.
The compressive force to urge a closing of the gap or spacing
between clutch members 38 and 40 is provided principally by a
spring assembly comprising a stack 8 of compression springs with a
minimal force as hereinbefore mentioned provided by wave spring 9.
Turning now to the spring assembly of FIG. 4, it will be noted that
wave spring 9 is inserted between washers 10 while the stack 8
includes a plurality (in the example shown 6) of conical washers
disposed between washers 10, and another common washer 10 being
utilized between the wave spring 9 and the top of the stack 8.
FIGS. 5 and 6 are deemed helpful in understanding the operation of
the device shown in FIG. 2 under minimum and maximum adjusted
torque limit settings respectively. These figures show the relative
position of clutch members 38 and 40 after the initial application
of sufficient torque required to flatten wave spring 9. FIG. 5
shows the relative position of clutch members 38 and 40 and bearing
7 with respect thereto for minimum torque setting and consequent
minimum compression of stack 8 urging upward to close the gap
between the opposing facing surfaces of clutch members 38 and 40
while FIG. 6 shows the relative position of parts for maximum
torque limit setting of the device. The minimum and maximum
settings set the gap between opposing face surfaces of clutch
members 38 and 40. The extent of this distance between opposing
face surfaces determines the height of the full depth of a recess
that a bearing 7 has to negotiate prior to clearing slots, e.g., 47
(see FIG. 3) and passing over the surface area 59 between the tops
of adjacent slots. Reduction of the distance between opposing
surfaces of clutch members 38 and 40 (as shown in FIG. 6) results
in a larger slot depth which must be negotiated (the device has
"bounced its clutch") by bearing 7 against the higher compressive
forces provided by adjustment of the amount of compression of stack
8.
Turning now to an understanding of the manner of operation of the
device and making reference to FIGS. 1 and 2, it will be noted that
a torque is applied through the handle of the customary mechanics
ratchet wrench (not shown) which has the stud thereof inserted in
the female receptacle in end 4, which torque also turns socket
engaging stud 3 at the same rate of speed and in unison with end 4
while the operator holds outer cylindrical housing sections 1
and/or 2, since bearings 7 retain slots 47 opposite slots 49. An
increasing resistance to the aforementioned turning is transmitted
to stud 3 by the item being tightened and wave spring 9 is first
flattened with clutch member 40 thus increasing the gap between
opposing facing surfaces of clutch members 40 and 38. In the case
of the minimum transmittable torque setting on the circumferential
scale inscribed on cylindrical housing section 1 or 2 (shown here
on section 2) with respect to the hairline on the opposing
cylindrical housing (shown here on section 1) stack 8 is under
minimum compression with only leaf spring 9 compressed thereby
allowing bearings 7 to almost clear the top of the V-shaped
recesses 47 as shown in detail in this condition in FIG. 5 and thus
the minimal amount of torque only applied against a minimum
compressive force on stack 8 clears bearings 7 to the next recesses
thus recycling the torque limiting device. In the case of maximum
torque limiting setting with less than 360.degree. of rotation (one
revolution) between cylindrical housing sections 1 and 2 from the
minimum torque setting, the compressive force on stack 8 is at a
maximum to urge the clutch members together to provide a minimum
gap therebetween as shown in FIG. 6 which maximum compressive force
must be overcome by the opposing resistive force supplied from the
work piece through stud 3 and clutch member 38 to the bearings 7
before bearings 7 can travel out of their respective slots to
negotiate the next slots in similar manner against a gap provided
there again by the preset compressive forces of stack 8. This
recycling continues as long as the applied torque continues to
exceed the selected torque limit. The torque limiting function is
provided by the present device independent of the direction of the
applied torque, e.g., clockwise or counterclockwise.
In a specific working embodiment of the present torque limiting
device adopted for use with a 1/2 inch drive ratchet handle, the
cylindrical housing comprising the two cylindrically shaped
sections had a diameter of about 21/4 inches and a length of about
21/4 inches, and the self-contained torque limiting device operated
over a useful range of 50 - 200 ft. lbs. torque. For a 3/8 inch
drive mechanics ratchet handle and a 1/4 inch drive handle, the
present cylindrically shaped housing would be relatively smaller,
and developing correspondingly less torque. The device may be
designed in accordance with the above teachings for various other
torque limiting spectra by varying the size of the housing to
accommodate compressive spring means having, e.g., a stack 8
containing a different number of compression springs. The present
torque limiting device, since similar in size and appearance to a
socket in a mechanics socket set may be stored in housings holding
such sockets conventionaly, utilized between ratchet handle and
sockets in the set, and adjusted by a simple vernier setting
between cylindrical housing sections to a reading in ft. lbs.
torque.
* * * * *